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A Ortíz

Publications and source records attributed to A Ortíz.

18 recordsLinked to original sources
PubMed1997

Limits of variation of fiber distribution in the sural nerve of man.

Although the sural nerve is the most extensively studied nerve in man, there is a dearth of data regarding the normal variations in the size-frequency distribution of axons in normal subjects; criteria for assessing the normality of a given individual are not available. Therefore, in everyday practice, the surgical pathologist may meet with difficulty in interpreting the biopsy of one particular individual, in whom the distribution is slightly different from the curves published. The object of this work is to detect the normal limits of variation in the distribution of diameters of myelinated and unmyelinated fibers in normal subjects and to establish the criteria that permit the calculated curves to be used in everyday clinical practice. Normal sural nerves of 19 patients were analyzed. Ages ranged between 18 months and 55 years. Morphometric analysis was performed with the Histoscan X automatic image processing analyzer, and, for statistical analysis, mixtures of lognormal distributions were fitted and tested with Pearson's statistics. Nerves of three diabetic patients were used for testing the method. They were clearly classified as abnormal. The curves, therefore, have been proven useful for everyday surgical pathology practice.

Adolescent↗
PubMed1996

Glomerular up-regulation of EIIIA and V120 fibronectin isoforms in proliferative immune complex nephritis.

Fibronectin: (FNs) comprise a family of adhesive glycoproteins that are prominent components of mesangial extracellular matrix and accumulate during glomerular injury. By alternative splicing of an unique mRNA precursor, various FN isoforms can be originated. In rat, three regions of the molecule are involved: EIIIA, EIIIB and V. Because specific FN isoforms are expressed in embryogenesis and wound healing, conditions characterized by cell migration and adhesion, we examined the pattern of FN isoforms in the mild and severe phases of a progressive immune complex proliferative nephritis in rats. We constructed specific probes to analyze the splicing pattern of FN pre-mRNAs by ribonuclease protection assays. FN mRNAs containing EIIIA, EIIIB and V regions increased along, the progression of nephritis, though the increment of EIIIB-FN mRNA was modest. However, different regulation of all these isoforms was observed. The percentage of FN mRNA containing the EIIIA exon versus total FN increased with the severity of the disease, while the percentage of FN mRNA containing the EIIIB exon decreased. Relative V-FN mRNA expression versus total FN mRNA increased only in the severe phase. By means of specific antibodies we also studied the presence of EIIIA, EIIIB and V-FN proteins in the kidney. In the normal glomerutus, EIIIA-FN protein was barely detectable in the mesangium, increasing in the mild phase of nephritis. In the severe phase of nephritis, increased EIIIA-FN was localized in the mesangium, in Bowman's capsule and in crescents. By contrast, EIIIB-FN protein in the glomerulus was absent even in the severe phase. V120-FN protein, an isoform that mediates the attachment of leukocytes through the VLA-4 integrin, was present in the mesangium and glomerular capillary loops in control animals, and increased in the severe phase of nephritis, coinciding with a strong leukocyte infiltration. In conclusion, our results show that during immune glomerular injury there were marked changes in the pattern of FN isoforms expression. Since those isoforms, particularly V120 isoform, are important in cell adhesion and migration, their up-regulation may facilitate the recruitment of cells into the injured glomeruli. The blockade of the interaction between V120-FN and infiltrating leukocytes may represent a new approach to the treatment of nephritis.

Alternative Splicing↗
PubMed1996

[PSA and PSAD study in patients with renal dysfunction].

This study analyzes the changes in serum and urinary PSA values in 28 subjects; 13 with creatinine clearance under 75 ml/mn and 15 with creatinine clearance over 75 ml/mn. Both groups were compared for prostate size, measured by transrectal ultrasound, prostate weight, serum PSA (SPSA), 24h urine PSA (PSAO), PSA clearance (PSACl), serum creatinine (SCr), creatinine clearance (CrCl), PSA density (PSAD), PSA/creatinine ratio (PSA/Cr) and PSACl/CrCl ratio. Mean values of SPSA and PSAO were 4.5 +/- 0.8 and 222 +/- 29.7 ng/ml respectively, values for SCr, CrCl and PSACl averaging 1.62 +/- 0.2 mgr/dl, 71.6 +/- 6.5 ml/mn and 150.5 +/) 32.9 ml/mn. Median prostate size was 32.6 +/- 3.9 cc, with weights of 40.3 +/- 4.9 g and mean PSA density (PSAD) 0.13 +/- 0.02. The results of the homogeneity study showed that there are no significant differences between both groups with regard to the variables considered in the study. SPSA values were higher in patients with CrCl < 75; 3.4 vs 5.7, but not significantly. There are no significant differences between PSAO and PSACl values for both groups, even though PSAO levels were higher in patients with CrCl < 75 ml/min (p = 0.1). PSAD values for patients with CrCl > 75 ml/mn were lower than those for patients with CrCl < 75 ml/mn; 0.09 vs 0.17 (p = 0.08). In the entire sample, PSAD levels showed correlation with SPSA and PSA/Cr values; R = 0.63 (P = 0.0003) and r = 0.5 (p = 0.009) respectively. Also, they were significantly but inversely correlated with PSACl levels; r = - 0.5 (p = 0.006) and PSACl/CrCl; r = - 0.048 (p = 0.01). No correlation was seen between PSAD values and the following parameters; PSAO (p = 0.7), SCr (p = 0.5) and CrCl (p = 0.27). When the group of patients with CrCl < 75 ml/mn is considered, PSAD values are correlated exclusively with PSACl values; r = - 0.69 (p = 0.008) and PSACl/CrCl; r = 0.68 (p = 0.009). Our data appear to indicate that there is a certain relationship between PSAD and the renal function although the physiopathological mechanism responsible for that is unknown. Nevertheless, considering the sample size, more comprehensive studies will be necessary to obtain more convincing results.

Aged↗
PubMed1995

Fibronectin (FN) decreases glomerular lesions and synthesis of tumour necrosis factor-alpha (TNF-alpha), platelet-activating factor (PAF) and FN in proliferative glomerulonephritis.

We have studied the effect of therapy with plasma FN on glomerular synthesis of PAF, TNF-alpha and FN, in experimental proliferative glomerulonephritis. Glomerular PAF, TNF-alpha and FN production were increased in rats with nephritis. Peak glomerular PAF production preceded, while peak glomerular TNF-alpha bioactivity coincided with maximal proteinuria. Rats treated with FN (5 mg/kg per 48 h) for 15 days had less proteinuria, glomerular and interstitial cell infiltration and glomerular PAF, TNF-alpha and FN synthesis than non-treated rats. In order to characterize further the mechanisms of action of FN, healthy rats were injected with either FN or saline. Peripheral blood mononuclear cells and neutrophils from healthy rats injected with FN secreted less TNF-alpha and PAF, respectively, than those obtained from saline-treated rats. Our data suggest that the beneficial effect of FN may be related to decreased number of glomerular leucocytes and decreased synthesis of inflammatory mediators and extracellular matrix.

Animals↗
PubMed1995

Specific PCR primers directed to identify cryI and cryIII genes within a Bacillus thuringiensis strain collection.

In this paper we describe a PCR strategy that can be used to rapidly identify Bacillus thuringiensis strains that harbor any of the known cryI or cryIII genes. Four general PCR primers which amplify DNA fragments from the known cryI or cryIII genes were selected from conserved regions. Once a strain was identified as an organism that contains a particular type of cry gene, it could be easily characterized by performing additional PCR with specific cryI and cryIII primers selected from variable regions. The method described in this paper can be used to identify the 10 different cryI genes and the five different cryIII genes. One feature of this screening method is that each cry gene is expected to produce a PCR product having a precise molecular weight. The genes which produce PCR products having different sizes probably represent strains that harbor a potentially novel cry gene. Finally, we present evidence that novel crystal genes can be identified by the method described in this paper.

Bacillus thuringiensis↗
PubMed1995

Clinico-pathological correlation in dementias.

The object of this study is to investigate whether or not there are clinical signs and symptoms in patients with dementia that, by themselves or jointly, can be associated with the pathological diagnosis of Alzheimer's disease. Twelve patients with dementia were studied, in whom the clinical diagnosis of Alzheimer's disease was made according to established criteria. A sample of leptomeninges, cortex and subcortical white matter was obtained from each patient and was processed for light and electron microscopy. In the cases in whom neuritic plaques and neurofibrilary tangles were present, pathological changes were quantified. The diagnosis of Alzheimer's disease was confirmed in 5 cases, whereas in 3 patients spongiform encephalopathy was present. In the remaining patients, the number of neuritic plaques was within normal limits for the age of the subjects. Comparison of the data in Alzheimer (n = 5) and non-Alzheimer (n = 7) groups showed an increased, statistically significant incidence of acalculia, abnormalities of judgment, impairment of abstraction and primitive reflexes in the former. Although good fitting models were obtained, none achieved perfect discrimination. The model that included alterations of judgment and acalculia gave the best fit.

Aged↗
PubMed1994

Estrus synchronization with melengestrol acetate in cyclic ewes. Insemination with fresh or frozen semen during the first or second estrus post treatment.

A total of 540 cyclic ewes were randomly allocated to 1 of 6 groups according to synchronization or not with melengestrol acetate (MGA), insemination with fresh or frozen semen, and insemination during the first or second estrus post treatment. The MGA was effective in synchronizing estrus, since the percentage of ewes showing estrus during the first 6 days after treatment was significantly higher (P<0.05) for treated (79.5%) than for nontreated ewes (33.5%); 74% of the treated ewes showed estrus during a 72-h period. Progesterone concentrations in plasma samples obtained at random from 34 treated ewes on Day 8 post estrus revealed that 94% of them ovulated and formed a functional CL. Synchronization was maintained during the second estrus post treatment, since 71.9% of the ewes showed the second estrus during a 72-h period. Treatment with 0.22 mg of MGA/head/d for 14 d had a detrimental effect on fertility when insemination was carried out during the first estrus post treatment. Delaying insemination until the second estrus post treatment caused a less marked reduction in conception rates. Thus, MGA can be a useful alternative for estrus synchronization of a large number of ewes. Artificial insemination can be delayed until the second estrus post treatment, improving fertility without loosing the advantages of estrus synchronization.

Journal Article↗
PubMed1994

Involvement of tumor necrosis factor and platelet-activating factor in the pathogenesis of experimental nephrosis in rats.

BACKGROUND: The experimental nephrosis induced in rats by adriamycin (ADR) or puromycin aminonucleoside (PA) provide a useful model to study the participation of inflammatory mediators in the pathogenesis of proteinuria. EXPERIMENTAL DESIGN: We have measured tumor necrosis factor (TNF) and platelet-activating factor (PAF) production by glomeruli of rats with nephrosis, as well as the effect of treatment with the PAF antagonist, BN52021. We have also evaluated the in vitro effects of ADR, PA, and PAF on TNF and PAF production, cell viability, and protein synthesis in glomerular mesangial cells and glomerular epithelial cells (GEC) in culture. RESULTS: In ADR nephrosis, the greatest production of PAF was on day 14, preceding maximal proteinuria, whereas the highest levels of TNF where observed on day 21 after ADR injection, the moment at which proteinuria reached maximal levels. In PA nephrosis, glomerular PAF production peaked twice (days 1 and 15), before and after maximal proteinuria (day 11), whereas TNF production peaked from days 2 to 11, and slowly declined until day 21. In both models, treatment with BN52021 induced a striking decrease in proteinuria, as well as a diminution in glomerular TNF and PAF production. Both ADR and PA induced TNF and PAF production in whole glomeruli, glomerular mesangial cells, and GEC in culture. As shown by a 51Cr release assay, ADR and PA were toxic to GEC. This effect was inhibited by PAF antagonists and by anti-TNF antibodies. Whereas TNF was moderately toxic to GEC, PAF had no effect on 51Cr release. TNF toxicity was abolished by anti-TNF antibodies and largely diminished by PAF antagonists. CONCLUSIONS: TNF and PAF may participate in the induction of GEC damage and the development of proteinuria in two experimental models of nephrosis in rats.

Animals↗
PubMed1992

Presence of circulating antibodies against brush border antigens (Fx1A) in a patient with membranous nephropathy and bilateral pyeloureteral stenosis. Comparison with idiopathic membranous nephropathy.

In a patient with membranous nephropathy and bilateral pyeloureteral stenosis with hydronephrosis, we examined the possibility that an increase in the intratubular pressure could facilitate the passage of the Fx1A antigens to the circulation. Elevated serum anti-Fx1A antibodies were detected in this particular patient by ELISA on three occasions during the disease follow-up, even though he was in clinical remission. These antibodies reacted in vitro with the tubular brush border of a normal human kidney. The anti-Fx1A antibodies isolated from the patient's sera by affinity chromatography competed with the rabbit anti-Fx1A antisera binding to plates coated with human Fx1A antigen. In immunoblotting studies the isolated specific IgG antibodies from that patient reacted with a 180 kDa antigen of the human Fx1A and with less intensity with 75 kDa and 50-55 kDa polypeptides. In none of 12 patients with idiopathic membranous nephropathy could the circulating anti-Fx1A antibodies be demonstrated. On the whole, this particular case suggests that on some occasions increased intratubular pressure could cause the release of Fx1A antigens, facilitating an autologous immunocomplex nephritis. These antigens, by contrast, do not seem to play any role in most cases of membranous nephropathy in man.

Aged↗
PubMed1990

Evidence suggesting a role for platelet-activating factor (PAF) in experimental nephrotic syndrome.

Sprague-Dawley rats injected with a single dose of adriamycin at 7.5 mg/kg/day developed an important and persistent proteinuria from day 14. Animals treated from day 0 to 3 weeks with PAF-receptor antagonists (BN 52021 or alprazolam) did not present (p less than 0.0005) the adriamycin-induced proteinuria or only to a very low extent. Furthermore, epithelial glomerular cells presented in these animals a normal aspect, while in rats injected with adriamycin, but not treated, the epithelial cells showed effacement of foot processes and intensive degenerative changes. By contrast, rats treated with steroids or cyclosporin did not present a significant reduction in proteinuria or improvements in epithelial cell lesions. Rats injected with adriamycin also presented an increase in the number of inflammatory infiltrating cells, chiefly la(+)-reactive cells (OX6+ cells), macrophages (ED1+ cells) and T-cytotoxic/suppressor cells (OX8+ cells). Concomitant administration of PAF-receptor antagonists induced a significant reduction in the number of these cells. Glomerular cells from normal control rats incubated with adriamycin incorporated 3H-acetate into a polar lipid with biological and migratory characteristics on thin-layer chromatography similar to synthetic PAF. On the whole, our data suggest a role for PAF in the pathogenesis of experimental nephrotic syndrome induced by adriamycin.

Acetates↗
PubMed1975

In vitro metabolism of 3-H-androstenedione by the male rat pituitary, hypothalamus, and hippocampus.

The in vitro metabolism of 2,2-3-H-androstenedione by the pituitary, hypothalamus, and hippocampus of intact and castrated adult male rats was studied. Conversion of androstenedione to radiochemically pure 5alpha-androstanedione, testosterone, 5alpha-dihydrotestosterone, androsterone, and traces of 3alpha, 5alpha-androstanediol was demonstrated in minced preparations of the three tissues in the absence of cofactors. 5alpha-androstanedione was the metabolite formed in the highest proportion. The pituitary showed the highest enzymatic conversions followed in decreasing order by the hippocampus and the hypothalamus. Castration performed three weeks prior to the experiments resulted in a significant decrease of pituitary 17beta-old-dehydrogenase activity with a concomitant increase of 5alpha-reductase. No significant changes were observed after castration in the hypothalamus and the hippocampus.

Androstenedione↗